The severe injuries which typically result from serious vehicle accidents are not always caused by the primary impact of the vehicle. Often, these injuries result from the secondary impact between the vehicle occupants and the vehicle interior after the primary impact has occurred. Additionally, these injuries often occur from fires resulting from the ignition of fuel by the ignition system. The fire danger is particularly acute when the accident results in the inversion of the vehicle.
The injuries due to the secondary impact can often be minimized through the use of seat belts. However, seat belts in vehicles are often not worn by the vehicle occupants because they can be somewhat uncomfortable and restrict movement in the vehicle. Accordingly, much effort has gone into the development of retractor mechanisms responsive to changes in the inertia of the vehicle. Such systems allow the seat belts to slacken until an emergency situation occurs, whereupon the seat belt system activates and restrains the movement of the vehicle occupants. Continuing development of seat belt retractor mechanisms has often utilized electrical devices to automatically activate the seat belt system in an emergency situation.
The injuries resulting from the fires occurring from the ignition of fuel by the ignition system can often be prevented if the electricity supplied to the ignition system is interrupted or if the supply of fuel is inhibited immediately after an accident. Consequently, devices have been developed which either interrupt the current supplied from the battery to the ignition system, or interrupt the fuel supplied from the fuel tank to the engine upon the occurence of an emergency situation.
The key element in electrically-activated seat belt systems and in those devices interrupting the ignition circuit or the fuel line is a switch responsive to changes in the inertia of the vehicle. Some of the switches found in the prior art generally utilize ball-shaped masses held upon conical seats by magnets. A change in the acceleration of the vehicle results in the unseating of the ball and the opening of an electrical contact. Other devices found in the prior art utilize mercury switches which break an electrical circuit upon a sufficient inertia change in the vehicle.
Generally, all of these devices are somewhat complicated mechanically and are not constructed to allow sufficient control over the device sensitivity to prevent activation of the switch when the vehicle encounters rough road or other normal shock. Those devices which have incorporated a sensitivity adjustment are not sufficiently sensitive to activate the switch upon certain shocks which result from loss of control of the vehicle, such as the overrunning of a curb. Additionally, many of the devices found in the prior art do not incorporate mechanisms for resetting the switch after activation of the switch has occurred. In those switches which have incorporated such mechanisms, the resetting mechanism is not designed for convenient use by the vehicle occupant.
Most importantly, the inertia switches found in the prior art are primarily sensitive to changes in the acceleration of the vehicle, and are not sensitive to inversion of the vehicle. As the danger from fire is greatest when the vehicle is inverted, the provision of a mechanism to insure activation of an inertia switch upon such inversion would greatly enhance the effectivity of an inertia switch. An inertia switch responsive both to momentum changes and to inversion would have wide-ranging application in a variety of vehicles. Such a device would greatly increase the safety of the vehicle occupants, and thus help to minimize the serious injuries which often occur in vehicle accidents.
Accordingly, it is the principal object of this invention to provide an inertia switch mechanism responsive to both a change in the momentum and an inversion of a vehicle in which the switch is installed.
It is an additional object of this invention to allow adjustability in the level of the momentum change necessary to cause activation of the switch.
It is still another object of this invention to simplify the design of inertia switches.
It is still another object of this invention to incorporate a convenient reset mechanism in an inertia switch.
It is a final object of this invention to minimize the danger to vehicle occupants resulting from secondary impact within the vehicle interior and from fires resulting from the ignition of fuel by the ignition system.